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Thread: Tricks to locate loose suppy line

  1. #1

    Default Tricks to locate loose suppy line

    I have a front load washer that uses very little water, but turns turns the water on/off many, many times during a cycle. There is a hot water hammer somewhere in the walls.

    While remodling the master bath shower, I found that there were no hammer arresters installed... which leads me to believe that they may not have been installed anywhere. Is this common, or would you expect to find them in other key locations? I suppose I could just install the "add-on hammer arrester" but frankly they are ugly and scream poor quality (not good when selling), and I've got a bag of straps ready to do their job.

    I tried to bleed the system, but the problem returned immediately.

    Tried a metal pipe locator, but have not found the pipe... thinking it may be in the joists. Is there any liklihood that it is more likely a horizontal vs vertical run? Any tricks of the trade to isolate the location...
    or is it time to start cutting up my floor and walls?

  2. #2
    Plumber Deb's Avatar
    Join Date
    Sep 2004

    Cool Deb

    If the water is turning off and on during a cycle, this is not water hammer--you have something else going on here. I would be checking the washers in the water valves to the washer. I would also be checking the water valve located in the washer.
    I never install water hammer devices.
    The Pipewench

  3. #3


    Thanks Deb,
    The valves work fine (they turn off and on, no leaks or drips). The banging occurs when the water stops, and I thought that was the cause of hammering.

    What else should I be checking for with the valves?

  4. #4
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    San Diego


    Although I NEVER argue with Deb, I think she misread your question. A banging noise when the valve turns off IS hammer. Rather than tracking down the exact loose pipe ( there could be many) you could open the wall near the WM and install sweat-in arrestors inside the wall. Use a real arrestor, such as from Sioux Chief or others, but not just an air chamber.

  5. #5


    hmmm... now I'm questioning the two air chambers that I just installed with a new shower... didn't realize that there were official arresters.

    Good idea - I can get into the wall pretty easily - so I'll try that. I guess if it doesn't work, at least I may be able to see where it's hammering.


  6. #6
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default hammer

    Air chambers work for a little while but once the air is absorbed into the water and it becomes "flooded" there is almost no way to recharge it. The water hammer is occurring because the valve closes rapidly, and that will not change even if you strapped the pipe every couple of feet. You need a arrestor, but make it accessible, because someday the piston's lubrication will "wear out" and the noise will come back.

  7. #7


    Thank you for your advice. I'll do what you suggest for the laundry room, and I'll leave an access panel for future maintenance. How long will the lube generally last?

    For the air chambers I installed upstairs, I was able to drain the system (before roughing in the shower) by shutting off the water to the house, and opening faucets downstairs. Am I missing something, or shouldn't that replace the air in the chamber?

  8. #8


    Ok, so I'm in the process of installing a set of in-wall SouixChief hammer arresters...

    while sweating the joint (used a "T" with a street elbow), the hammer arrester "poped" out of the joint. I was too hot to touch, and I'm wondering if the non-metal parts inside are now toast. Obviously, I'd like to know before I repressurize the system.

    With shower valves, you can pull all the rubber parts out - so they don't get damaged by the heat... can't see how I could pull that off with the arrester.

    Ok, now after my daily visit to Lowes, I have a pluthera of options. Just in case, I purchased another arrester, and I bought a set of the screw-on (in wall) type. So at this point - I have many options:
    1) Leave the one as is (I guess if it's busted, it'll still have an air chamber)
    2) Replace it with another
    3) Replace it with a female thread adapter and the screw-on version
    4) Replace it with a standard air chamber

    Quote Originally Posted by jimbo
    Use a real arrestor, such as from Sioux Chief or others, but not just an air chamber.
    Quote Originally Posted by hj
    Air chambers work for a little while but once the air is absorbed into the water and it becomes "flooded" there is almost no way to recharge it.
    Also, I was thinking about this - if I shut the water off, and opened other valves on the line, then used my air compresser to "push" 30 PSI of air through the laundry valves (and the air chamber was installed in the immediate vertical drop from the valves), then once the water in the line were pushed down past the air chamber ("T" w/ street 90), shouldn't that allow any water in the chamber to gravity flow down the pipe? When the pressure came back on, the chamber would be filled with air again.

    I guess I'm just trying to better understand this stuff, and my "air" solution seems a lot easier to maintain than replacing the piston versions. And I don't want to burn through another piston with heat?

    I look forward to your feedback!

    Help & Thanks!
    - Michael
    Last edited by DIYMike; 02-08-2005 at 12:28 PM.

  9. #9
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default aair chamber

    Stick a straw into a glass of water until it is full then put your finger over the end. Now try to get the water out without tipping the straw upside down. That is your air chamber and the water is not going to drain unless you can get air into the chamber above the water. And that is not going to happen.

  10. #10


    Thanks hj,
    Well, the straw melted when I tried to sweat it, but I just tried your experiment with a piece of 1/2 copper... and it drained.

    I'm really not trying to be difficult.

    btw - I've finished. I went with option #1. Seems to work. Ironically, when I was putting the wall back together, I found the culprit. It was the cold water pipe banging against a gas line. unfortunately, I didn't see it until I trimmed back the drywall (further than I originally needed). I put a plastic 1/2 pipe holder around the supply line, between it and the gas line... no more noise.

    2 fixes, 1 big hole. Thanks for your help.
    Last edited by DIYMike; 02-08-2005 at 04:00 PM.

  11. #11
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default pipe

    You did not try it in an actual installation.

  12. #12

    Default Anyone every try an air chamber?

    Well, if I try it in an actual installation, then how will I know if it works

    Reminds me of that "if a tree falls in the woods"...thing.

    Seriously, I found the air chamber solution in a book, and I'm curious if anyone else out there actually uses them.

  13. #13

    Cool Air Chambers

    The use of air chambers is out dated and no longer an approved method to control water hammer shock. Check the copyright on your book as it probly isn't very recent.
    Read this and see the proper devices that are now approved by the plumbing code bodies for use in effectively controlling water hammer for the long term.

    Water hammer exists in a water distribution system with quick closing valves even if you don't actually hear it. There is still the "shock" of the water that can eventually lead to failed appliances, valves, pipe, or fittings.

  14. #14


    Thanks for the link. Makes sense to me.

    So - I ran the first load of laundry last night and no audible hammer (the pipe banging that I was trying to fix in the first place was GONE!!).

    As I mentioned, the cold supply was touching a gas pipe, and when I tapped on it, it recreated the sound up the walls. So, in addition to the arresters, I placed a plastic ring around the suppy line to prevent it from touching the gas line.

    When I installed the souix-chief sweat-on model on the "hot" supply, it suddenly popped off. I (stupidly) immediatly put it back on and finished sweating it. Now of course, I have no idea if it's toast. When I installed another one on the cold line, i was much, much more careful with the heat, and no popping occurred.

    Has anyone had this experience? Did that "pop" toast the arrester? Would I be able to tell if I took it off? Should I?

  15. #15

    Default Book: Stanley - Complete Plumbing @2003

    I believe you ...


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